We (Decagon Devices) are developing an instrument to measure physical properties of the Martian soil and atmosphere in situ for the Mars Phoenix 2007 Scout Mission. This probe, the Thermal and Electrical Conductivity Probe (TECP), will measure soil thermal properties (temperature, thermal conductivity, and volumetric heat capacity), soil electrical properties (electrical conductivity and dielectric permittivity), and atmospheric properties (wind speed, water vapor pressure). TECP will be mounted on the Phoenix robotic arm, and have the capability to take measurements at multiple depths in an trench made by the robot arm scoop. Atmospheric measurements will provide insight into water transport in the vapor phase. Direct measurement of regolith thermal properties will improve existing estimates of thermal inertia and better current understanding of how heat penetrates the Martian regolith in response to diurnal or seasonal cycles. Measurements of regolith electrical properties will identify the presence of any unfrozen water that might result from incident sunlight on the freshly exposed icy soil in the trench.